(1) Field of the Invention
The present invention relates to a method and apparatus for fabricating a flexible liquid crystal display device and a substrate base material for the flexible liquid crystal display device.
(2) Description of Related Art
Liquid crystal display devices each have a liquid crystal layer sandwiched between a pair of substrates. Typically, a pair of glass substrates are used as the pair of substrates. Methods for fabricating a liquid crystal display device include the following known methods: a method in which liquid crystal material is dropped onto one of the pair of glass substrates and then the glass substrates is bonded to the other glass substrate; and a method in which the pair of glass substrates are previously bonded to each other and then liquid crystal material is vacuum-injected into cells formed between the pair of glass substrates. Both the methods need be carried out inside a vacuum container.
By the way, it has been known that when, instead of the glass substrates, flexible plastic substrates are used for liquid crystal display devices, images are displayed with the whole liquid crystal display devices curved significantly. Applications of the liquid crystal display devices include electronic paper and wearable displays, such as watches.
When a plurality of liquid crystal display devices with a pair of plastic substrates are fabricated, they are preferably fabricated spatially continuously from a pair of rolled or long-sheet-like plastic substrate base materials in terms of the improvement of production efficiency.
However, it is difficult to contain the whole plastic substrate base materials inside the vacuum container, because the plastic substrate base materials inevitably become relatively large. Furthermore, the production cost increases, because the vacuum container itself must be made larger.
To cope with this, it has conventionally been known that each base material is sectioned into liquid crystal cells by a double-seal structure, all adjacent pairs of the liquid crystal cells are allowed to communicate with each other through a connection path, and liquid crystal material is not injected into the liquid crystal cells inside a vacuum container (see, for example, Japanese Unexamined Patent Publication No. 62-150283).
More particularly, seals are provided on the top surfaces of the plastic substrates to surround the liquid crystal cells, respectively, and then the plastic substrates are bonded to each other by a pressure roller. A little larger amount of the liquid crystal material than a necessary amount thereof is dropped onto the liquid crystal cells at the position at which the plastic substrates are bonded to each other. In this way, air bubbles in the liquid crystal material are expelled through the connection path.